Caffeinate Around The Clock

7 A.M.

Wake up and burn. The caffeine in 1 cup of joe temporarily revs metabolism by up to 15 percent, torching an extra 15 to 25 calories, says Paul Arciero, Ph.D., associate professor of exercise science at Skidmore College in Saratoga Springs, New York. It's not yet clear whether drinking more delivers a bigger boon, but for the most burn, order yours black; sugar and milk reverse the fat-scorching effects.

9 A.M.

Offer to make a coffee run. Asking for a raise? Hand the boss a latte before your next meeting. Downing a moderate amount of caffeine may make a person more open to persuasion, a study in the European Journal of Social Psychology reports.

Noon

Painproof your workout. Stop by a café on your way to the gym. Because caffeine seems to block signals of muscle fatigue, both cardio and strength training feel easier, letting you work harder or go faster without noticing extra exertion. Note to insomniacs: If coffee keeps you up at night, make this cup your last one of the day.

3 P.M.

Power through a slump. Be the belle of the conference room. Taking a coffee break can leave you happier and more sociable, says Laura Juliano, Ph.D., a caffeine researcher at American University in Washington, D.C. And the amount in 1 cup helps you concentrate and feel alert at your desk.